Marie Anne was said to have been the fruit of her mother's affair with François Louis, Prince of Conti. Her mother, who had an amorous nature, had been having an affair with the prince in the time leading up to the birth of Marie-Anne. François Louis's wife, Marie Thérèse de Bourbon, was the sister of Marie-Anne's mother's husband. Together, the Conti couple had been the titular monarchs of Poland during the year of Marie-Anne's birth.